DIFFUSION: This is defined as the process by which molecule or ions of a substance (i.e. gases and liquid) move from a region of high concentration to a region of low concentration until they are evenly distributed. The substance involved in diffusion may be liquid, gases or solid.
FACTORS AFFECTING DIFFUSION
The rate or speed of diffusion is controlled by a number of factors which include;
i) STATE OF MATTER: Diffusion varies with the three of matter. The diffusion of gases is much faster than that of liquids because the gas molecules are freer and therefore faster than liquid molecules.
ii) MOLECULAR SIZE: The nature or the size of the molecules affect diffusion. In general, the smaller the molecules, the faster the rate of diffusion while the larger the molecules the slower the rate of diffusion.
iii) DIFFERENCES IN CONCENTRATION: For diffusion to take place in a medium, there must be differences in the concentration of the substance in two areas. The greater the differences in the concentration of the molecules the greater the rate of diffusion.
iv) TEMPERATURE: High temperature increases the speed at which molecule move. Thus, the higher the temperature the faster the rate of diffusion.
Osmosis is defined as the flow of water or solvent molecules from a region of dilute or a weaker solution to a region of concentrated or stronger solution through a selectively or differentially permeable membrane.
CONDITIONS NECESSARY FOR OSMOSIS TO TAKE PLACE
There are three major conditions which are necessary for Osmosis to take place.
i) Presence of a stronger solution e.g. sugar or salt solution.
ii) Presence of a weaker solution e.g. distilled water.
iii) Presence of a selectively or differentially permeable membrane.
Plasmolysis is defined as the outward movement or flow of water from living cells when they are placed in a hypertonic solution. Plasmolysis is often regarded as opposite of osmosis.
Haemolysis is defined as the process by which red blood cells or corpuscles become split or burst as a result of too much wider passing into it.
Turgidity is defined as the condition in which cells absorb plenty of water up to a point where the cell is fully stretched. At this point, the cell is said to be turgid. Turgidity occurs when a cell is placed in an hypertonic solution.
Flaccidity is defined as the condition in which plants lose water to their surroundings faster than they can absorb. When a plant looses more water. It is said to be flaccid.
PROPERTIES AND FUNCTIONS OF THE LIVING CELL
All living cells are made up of seven major types of materials. These materials include proteins, carbohydrates, water, fats and oils, vitamins, minerals and nuclear acids.
The metabolic processes are very important for life. If they stop, the cell will die. Therefore the cell is capable of carrying out nutrition, respiration, excretion, growth, movement, reproduction etc.
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